The present invention relates to an exposure calculation method and a radiography system, and more particularly, to a method of calculating an exposure a patient receives during radiography, and a radiography system including means for calculating the exposure a patient receives during radiography.
A radiography system controls an X-ray exposure so that the X-ray exposure will be set to a predetermined value. The predetermined value is, for example, a minimum necessary exposure. For the control, a dedicated detector is used to detect or monitor an X-ray exposure during radiography. When a value resulting from the temporal integral of the components of a detection signal reaches a predetermined value, X-irradiation is stopped (refer to, for example, Patent Document 1).
[Patent Document 1] U.S. Pat. No. 5,694,449 (third to fifth columns and FIG. 1 to FIG. 4)
According to the above method, the dedicated detector is needed for detecting an X-ray exposure during radiography. Moreover, a signal processing circuit or the like is needed for performing predetermined processing that includes the temporal integral of the components of the detection signal. Therefore, the method is unsuitable for, for example, a mobile radiography system and other radiography systems requested to have a simple configuration, be lightweight, and cost low.